I have a CIS printer and dilute even further, usually a 5:1 ratio (it becomes slightly bluish beyond that point), but even as-is 100mL will print far more than 50 pages -- probably closer to 5000 if not more. At that point the cost of paper becomes more significant.
Edit: it looks like the other colours are the same price (when I last bought ink, which was a long time ago, CMY was slightly more expensive):
http://www.3000rpm.com/acatalog/Epson-Continuous-Ink-System-...
I have a CIS printer and dilute even further, usually a 5:1 ratio (it becomes slightly bluish beyond that point), but even as-is 100mL will print far more than 50 pages -- probably closer to 5000 if not more. At that point the cost of paper becomes more significant.
Edit: it looks like the other colours are the same price (when I last bought ink, which was a long time ago, CMY was slightly more expensive):
http://www.3000rpm.com/acatalog/Epson-HP-Canon-Brother-Conti...